Description and etiology of paleopathological lesions in the type specimen of Parasaurolophus walkeri (Dinosauria: Hadrosauridae), with proposed reconstructions of the nuchal ligament

• DOI: 10.1111/joa.13363
• Publication Date: 2020-12-02T04:57:36Z
• Authors: Filippo Bertozzo; Fabio Manucci; Matthew Dempsey; Darren H. Tanke; David C. Evans; Alastair Ruffell; Eileen Murphy
• Keywords: Paleopathology

Abstract Paleopathology, or the study of ancient injuries and diseases, can enable ecology life history extinct taxa to be deciphered. Large‐bodied ornithopods are dinosaurs with highest frequencies paleopathology reported to‐date. Among these, crested hadrosaurid Parasaurolophus walkeri is one most famous, largely due its dramatic elongated tubular nasal crest. The holotype at Royal Ontario Museum, Canada, displays several paleopathologies that have not been discussed in detail previously: a dental lesion left maxilla, perhaps related periodontal disease; callus formation associated fractures three dorsal ribs; discoidal overgrowth above neural spines six seven; cranially oriented spine seven, merges distally six; V‐shaped gap between seven eight; ventral projection pubic process ilium which covers, fused with, lateral side iliac pubis. These lesions suggest animal suffered from more traumatic events, main causing suite anterior aspect thorax. presence single individual rare observation and, comparison substantial database hadrosaur paleopathological lesions, has potential reveal new information about biology behavior these ornithopods. precise etiology abnormality still unclear, although it thought an indirect consequence trauma. two also seems secondary severe trauma inflicted on ribs spines, probably represents post‐traumatic ossification base nuchal ligament. existence this structure previously considered hadrosaurs generally through origin insertion sites modern diapsids ( Rhea americana , Alligator mississippiensis Iguana iguana ), but presence, structure, origin‐attachment debated. hypothesized as representing point stresses ligament, pulling forward, ossified tendons posterior backward. Different reconstructions morphology based pathological conditions affecting ROM 768 proposed. Finally, we review for showing how erroneous misconceptions perpetuated over time led development hypotheses, including wide neck model supported current research.